The use of lime to remove sulfur dioxide from gaseous streams, such as combustion gas streams from combustion systems of power plants, is a proven technology which uses a wet scrubbing unit. Generally, an aqueous slurry of lime is charged to a wet scrubbing unit for countercurrent flow to a flue gas stream passing through the wet scrubbing unit, with formation of calcium sulfite and calcium bisulfite through reaction of the lime with the sulfur dioxide present in the flue gas. A major improvement in early such lime scrubbing processes was the provision of an effective amount of magnesium ions in the aqueous scrubbing slurry that significantly improved the efficiency of such processes. The magnesium-enhanced lime scrubbing processes, as described, for example, in U.S. Pat. Nos. 3,919,393 and 3,919,394 to Joseph Selmiezi, have become commercially accepted. In such magnesium-enhanced lime scrubbing processes for sulfur dioxide removal, the solids content of the aqueous scrubbing medium in the wet scrubbing unit is normally maintained with a range of about 3-10 percent by weight. Such magnesium-enhanced lime scrubbing processes normally produce a large supply of calcium sulfite which has either been disposed of in sludge ponding or has in one manner or another been transformed into a useful by-product, such as gypsum. In U.S. Pat. No. 4,976,936, to Ronald J. Rathi and Lewis B. Benson, for example, which is assigned to the assignee of the present invention, a calcium sulfite-containing aqueous discharge from a magnesium-enhanced lime scrubbing process is passed to a thickener and an aqueous sludge from the thickener is passed to a mixing tank where sulfuric acid is added to dissolve the calcium sulfite and the resultant solution is oxidized to produce a gypsum product that is separated from the aqueous media. Also, as described therein, if desired, a portion of the discharge from the scrubber may be passed directly to the mixing tank, by-passing the thickener, and mixed with sulfuric acid prior to oxidation. In such a process, a large scale thickener is required to handle the aqueous slurry discharged from the wet scrubbing unit and sulfuric acid must be added to the mixer.